Although I recomend not painting your wall, for those who cant resist the urge to paint.
there is now a range of textured paint avaliable in most hardwares and paint stores.

However I would leave the climbing surface of your woodie unpainted for a couple of reasons.

Textured paint will wear your skin and shoes (leave that to real rock) and is not much use in any overhanging parts of the wall.

Normal paint can be very slipery and your holds will spin. Also If you tighten down you holds to much on a painted surface it can cause the hold to stick like glue if you leave it for a while. I had to hammer a lot of holds off after not useing my wall for a month or so. The stuck holds didnt need bolts they could support even a dyno!